Beyond the Purdue Model: Rethinking Segmentation & the Industrial DMZ
From static perimeters to dynamic enclaves: modernizing the Industrial DMZ for connected & secure operations.
For years, industrial networks adopted the classic Purdue Model — layered zones, perimeter firewalls, and a dedicated Industrial DMZ. But in today’s world of cloud-connected operations, converged IT/OT networks, remote access, and rapid manufacturing change-cycles, the traditional Industrial DMZ has become static, exposed, and brittle.
The problem with the old approach
The Industrial DMZ was conceived as a perimeter buffer, between enterprise IT and plant-floor OT — a static zone that protected everything behind it.
But it's a heavy architecture to put in place and maintain with a lot of redundant equipments.
And operational realities — third-party remote support, IIoT sensors, cloud analytics, edge computing — break the assumptions of isolated zones and unidirectional flows.
As a result, the old model often leads to flat attack surfaces, lateral-movement risk, and slow change-cycles.
While models such as Beyond Corp emphasise identity, zero-trust, and software-defined controls, many industrial implementations still rely on legacy DMZ architectures.
Introducing Micro-DMZs and Enclaves
It’s time to move beyond the Industrial DMZ — and embrace micro-DMZs, deployed at or in front of each asset, providing dynamic, identity-centric, software-defined segmentation.
Instead of one big DMZ with static rules and fixed zones, think “per-use case DMZ overlay”: each machine or control system is protected by a micro-DMZ, managed through an enclave.
Access is no longer granted based on network location (Zone 2/3), but on identity, context, and real-time posture, with graceful degradation rather than outright denial when conditions aren’t fully met.
The micro-DMZ approach allows agile deployment, incremental rollout, and aligns with zero-trust and overlay networking principles.
Why this matters for industrial networks
Modern manufacturing cannot pause production to rebuild network zones or rip out infrastructure — so an overlay approach makes sense.
Micro-DMZs reduce attack surface by limiting lateral movement, and shrink the “blast radius” of any asset compromise.
They allow inter-zone flows (IT→OT, OT→IT, cloud analytics, remote support) to be dynamically permitted under least-privilege rules rather than broad zone rules.
They support a future-ready architecture, where each asset becomes a controlled enclave, part of a broader software-defined fabric.
A roadmap for modernization
Inventory & classify your OT/IT assets and flows: map what lives in the old DMZ and what still depends on it.
Design micro-DMZ overlays in front of critical assets: each with access gates, identity verification, and context-based rules.
Incrementally deploy the overlay on top of the existing network — no massive rip-and-replace required.
Shift to identity-first controls and software-defined segmentation, moving away from static zone-based rules.
Monitor and refine: track flows, tighten rules, segment further as new assets or flows appear.
To go further
Overlay Networking
Secure and segment an existing infrastructure — without touching the underlying physical network.
2025 State of Ransomware
Our analysis show an increase of 47% vs 2024, with roughly 56% of attacks targeting industrial companies.
ROI Analysis
Modernizing your industrial network shouldn’t mean ripping out what already works. Get ROI Analysis elements.